Build a cutting laser from an old PC

[Drake Anthony] makes building a cutting laser from a PC look easy, and it seems like it actually is. Almost everything you need can be found in a dead desktop unit. The diode is pulled from a DVD writer (16x or faster), with the power supply unit, and heat sinks from the processor and GPU being used as well. You’ll also need a focusing lens (just a few dollars), some thermal glue, an LM317, a resistor, and a pair of protective goggles matching the laser diode’s wavelength.

He fits the diode into the lens, then glues the assembly into a hole drilled through the processor heat sink. A driver is built using the LM317 variable regulator, resistor, power supply, and the GPU heat sink to keep things cool. Check out the video after the break to see the laser cutting tape, burning plastic, and lighting matches.

@xeracy – output power is somewhere between 100 and 200mW, probably. Depends on the speed factor of the burner.

Also, I don’t think that you can overdrive it much in continuous mode, especially if you don’t make use of the beam monitoring diode. Most laser diodes don’t like it for thermal reasons. It might be possible if pulsed, though.

Just rescue 20 of these and aim them at the same point. You could power a few(4-6) of these off the same PSU without too much trouble.
If you get them for free or nearly so it might actually be worth the time and expense spent on making a bulk mounting/aiming bracket.

Serious overkill.
The laser diode doesn’t generate enough heat to need that heatsink, a 20W laser doesn’t use one that big. The heatsink it is mounted to inside the drive is big enough. For power the lm317 isn’t needed. Use the 3.3V power from the power supply and feed it through a resistor. Output is around 120mw for dvd burners at 2.4V.

@Jesse, He pulled the northbridge heatsink off too, but it was half the size. Regardless of which I don’t think you’d need much of a heatsink at all. Those Axis modules work rather well dissipating the heat.

@cgmark, constant current drivers are important for driving lasers. A DVD laser may be fine, but a bluray laser has an incredibly steep I/V curve. Variances in laser diode construction produce different voltage drops and with resistor values and voltage drops that low you could quite easily use the resistor for one laser diode just fine, and then blow the next, especially when you run the laser at it’s limit.

@Gmc
I’m going to assume that there would be some amount of interference, but I have no idea how much. Assuming you’re driving them at the same voltage/current and the diode tolerances are pretty tight the light should be fairly monochromatic so there wouldn’t be too much loss due to that but so I guess most of the losses would be due to the mount and orientation of the diodes.
They’re using multiple lasers to try and drive fusion reactors so the problem isn’t unsurmountable. It just depends how much math you want to do, it would probably be easier to add a few more diodes to make up for losses.

@cgmark
I was basing my guesstimate on an old psu I had lying around which had 12v @ 9.5A through the yellow and the max current a Lm317 can handle 1.6A. So the number of diodes will vary depending on the size of the PSU, and obviously current from the diode.

@Garbz
I make driver circuits for 10W and 20W lasers so I’m familiar with what they require. bluray lasers will work fine off resistors alone but if you need current control the cheapest way is a transistors and resistors. The common PN2222A will do the job .

Diode lasers are nowhere near as complex as when we had to use high voltage and gas filled tubes with water and refrigerant cooling.

Using multiple lasers for a single source isn’t all that hard if you have the money to spend on the optics. The quality of optics is really all over the place depending on your budget.

@medward1 Cheap lasers that cut steel are typically CO2 laser tubes sourced from China. Water cooled, buy a bottle of CO2 (most gas supply places actually have the proper mix for lasers), a regulator, the transformer, and you’re in business. There are also sealed units that don’t need flowing CO2 but they have less power.

You could probably get started cutting metal for about $600, with a self-built CNC setup at around $3000.

You will be able to burn leather, I have done this using DVD diodes, but you need some goggles, or a CNC type thing :),
Or, use a webcam to look at the laser behind your LCD and just look at your LCD with your hands behind it, (Like working with one of those biohazard chambers with gloves)…
It works well for IR diodes too, cause the webcam can see those :)

I realise this video focuses on cheap laser construction… and hats off to that. But I can’t help bitching about the fact that too many youtube vids demonstrate lasers with burning tapes, matches and balloons. Would be more interesting to see actual experiments that require powerful lasers…

@ Brad
As the creator has already stated a red laser is bad at burning red/pink flesh. Enough of the laser is reflected/scattered when it hits your flesh to be a poor wavelength for burning you. In industrial processes they use different wavelengths for cutting different materials.
In Terms of overall wavelength energy (N)IR/red have the lowest energy with blue/UV having a lot of energy, enough so to break bonds on a molecular level and cause mutations in DNA ie; skin cancer from sun bathing.

As a kid, I found a big fresnel lens designed to turn a 19″ TV screen into something, uh, bigger, I guess. A few pine boards to make a frame and I discovered it could fry things much larger than ants. If the sun was in the right place, anyway.

It turns out that 4 ~300 watt photoflood bulbs in metal reflectors, a used box fan and some 2×4 stock makes a very effective portable death-ray, at least for small enough values of death.

Welder’s goggles are a must, but the budding mad scientist must remember that when you’re the only guy with a racoon tan in a place without ski hills.

Also, attempting to double the power to eight bulbs teaches you a lot about circuit breakers and introduces you to the physics of waste heat faster than you can say “Did you see that? It exploded!” and start picking fresnel lens shards out of the back yard.

You know, I’ll bet the arduino guys look at me like I look back at the teenagers who played with dynamite.

I’m pretty certain that when my little grand-daughter gets sent home from school for setting up a plasma disruptor field on the playground, I’ll be there to console her with ice cream, a largish bag of dilithium rock tailings and an explanation of how we can grow crystals in the oven.

Now that’s the way I like to approach technological experiments. Reminds me of when I needed to put a few holes in the bottom of my trash cans for rain drainage and there was this very handy .22 lying about. Do be advised some folks may not be all that open-minded about such experimental processes. Oh well.

Yes an old idea but still impressive in the way that it was put together, very resourceful and intelligent! I think that this particular design would be great for soldering because of the extended use ability and if it can generate enough heat to melt solder that would be awesome!! Nice design Drake!